According to the various quotes I've read there's no "non-public information" requirement.. just the vague "for business purposes" part.
While Twitter is the obvious example, what about a Github account? I've patched bugs or merged pull requests for my employer's projects from my own account. Would that qualify?
You should be careful about letting your employers' code hit your personal Github site for other reasons; an employer who wants to make it difficult for you to get a new business started can use IP issues to accomplish that.
Personal Github accounts are already a little bit fraught for that reason. The Illinois statute revision doesn't change the calculus; if you're an IL employee with a Github account you care about, you (a) don't want to be working for anyone who demands credentials to it, and (b) now have an avenue to extract a few tens of thousands of dollars from that employer should they ever be dumb enough to ask and then fire you.
While Twitter is the obvious example, what about a Github account? I've patched bugs or merged pull requests for my employer's projects from my own account. Would that qualify?